1 C. butter
4 romaine hearts, split in ½ lengthwise
4 garlic cloves, peeled and sliced
2 medium Spanish onions, cut into medium dice
1 thyme sprig
¾ C. sherry wine vinegar
Preheat oven to 325°. Place a high-sided, ovenproof skillet on medium heat and add the butter. When the butter is melted, increase the heat slightly. Place the romaine hearts, cut side down in the skillet and brown the leaves. Once brown, remove from the pan and set aside.
Lower the heat back to medium. Add garlic, onions and thyme sprig. Sweat the onion and garlic until translucent and soft, about 3-5 minutes. Once it’s at this stage, deglaze the pan with the sherry wine vinegar and cook this down until the vinegar smell disappears.
Add romaine hearts to the liquid, cover with aluminum foil. Cook in the oven for 20 minutes or until leaves are soft.